I am a do it early to get the good chunk of breakin out. I would have done it at 10,000 miles. I bet 60% of breaking crud is the at that mileage. Might as well get that high level out early. I did 3 early trans and diff dumps on my Hyundai after seeing my wife’s RAV4 rear diff dump black diff oil at 22,000 miles. I had dirty oil in my Hyundai rear diff at 2,500 miles if I remember the mileage correctly. It took 28,000 miles to stop the dirty rear diff shedding. I think I did 3 or 4 dump at 28,000. I was doing it more as a research posting on the Hyundai forums, and surprised how dirty it kept come out at early mileage break in.